Thu·Jan 5, 2023Thursday·January 5, 2023

1. 01*

   Challenges to the Good-Walker paradigm in coherent and incoherent photoproduction

   Spencer R. Klein🇺🇸

   High-energy vector meson photoproduction is an important tool for studying the partonic structure of matter at low Bjorken$-x$. In the Good-Walker (GW) paradigm, the cross-section $d\sigma /dt$ for coherent production of vector mesons or other final states, depends the average transverse distribution of gluons, while the incoherent cross-section depends on fluctuations in the nuclear structure, due to variations in nucleon positions, and/or gluonic hot spots. However, predictions of the the GW paradigm seemingly conflict with data from multiple experiments which observe coherent production of vector mesons accompanied by nuclear excitation, or in peripheral relativistic heavy-ion collisions. These data are consistent with a simpler, semi-classical approach. We will discuss this contradiction and explore how and why GW fails. We will also contrast the significant differences in incoherent photoproduction on ${}^{197}$Au and ${}^{208}$Pb targets in the GW approach with the much smaller expected differences in their low$-x$ gluon content.

   hep-phnucl-thPRC(2023)·18 citations
2. 02*

   Spin Polarization and Anomalous Magnetic Moment in a (2 + 1)-flavor Nambu-Jona-Lasinio model in a thermomagnetic background

   Yi-Wei Qiu🇨🇳 · Sheng-Qin Feng🇨🇳

   We investigate the magnetized QCD matter and chiral phase transition in a (2 {\th} 1)-flavor Nambu-Jona-Lasinio (NJL) model at finite temperature and chemical potential by comparing the contributions from the tensor spin polarization (TSP) and anomalous magnetic moment (AMM) of quarks. For light u and d quarks, when TSP and AMM are not considered, the magnetized system is characterized by magnetic catalysis. The introduction of TSP will further enhance the magnetic catalytic characteristics. On the other hand, when AMM is introduced, the phase-transition temperature decreases with the magnetic field, which is the feature of inverse magnetic catalysis. The phase diagram of u and d quarks will change from the crossover phase transition to the first order phase transition with the increase of magnetic field and chemical potential when AMM is induced. The phase diagram will not change from the crossover phase transition to the first-order phase transition when TSP is induced. For the phase diagram of strange s quark, whether TSP or AMM is induced, the phase diagram will keep a crossover phase transition with the increase of magnetic field and chemical potential.

   hep-phPRD(2023)·15 citations
3. 03*

   $B-L$ model in light of the CDF II result

   Sanjoy Mandal🇰🇷 · Hemant Prajapati🇮🇳 · Rahul Srivastava🇮🇳

   Recent CDF II collaboration's result on $W$ mass measurements contradict Standard Model prediction, requiring new physics to explain this anomaly. Such new physics may manifest through tree-level or loop-level corrections to the mass of the $W$ boson. In this work, we investigate the possibility that the CDF-II result is indicative of new physics not directly changing the $W$ boson mass but rather the $Z$ boson mass. Since the $Z$ boson mass goes as an input into the Standard Model prediction for $W$ boson mass, this change in $Z$ mass ultimately leads to the discrepancy between the CDF-II measurement and the Standard Model expectation. We demonstrate this idea through one of the simplest and most studied $U(1)$ gauge extensions of the Standard Model, namely the gauged $U(1{)}_{B-L}$ extension. We demonstrate that $B-L$ extended models can explain the revised best-fit values for $S$, $T$, and $U$ following the CDF II results. We studied the parameter space of models with and without mixing between neutral gauge bosons. We also reviewed the dark matter constraints and demonstrated that there is parameter space that is compatible with the current $W$ boson mass, relic abundance, and direct detection experiments.

   hep-phJ.Phys.G(2025)·10 citations
4. 04*

   Covariant orbital-spin scheme for any spin based on irreducible tensor

   Hao-Jie Jing🇨🇳 · Di Ben🇨🇳 · Shu-Ming Wu🇨🇳 · Jia-Jun Wu🇨🇳 · Bing-Song Zou🇨🇳

   In hadron spectrum physics, the partial wave analysis is a primary method used to extract properties of hadronic resonances. The covariant orbital-spin coupling scheme holds unique advantages over other partial wave methods due to its Lorentz covariant form and determined orbital-spin quantum numbers. This paper presents a general form of the covariant orbital-spin coupling scheme based on the irreducible tensor of the homogeneous proper Lorentz group and its little groups. A systematic procedure for constructing partial wave amplitude in a Lorentz covariant way is provided, which can be applied to both massive and massless particles. Specific examples are also included.

   hep-phhep-exhep-thJHEP(2023)·7 citations
5. 05*

   Study of new physics effects in lepton flavour violating B decays into K2^star(1430)l1 l2

   S. Biswas🇮🇳 · M. Mandal🇮🇳 · S. Mahata🇮🇳 · S. Sahoo🇮🇳

   Lepton flavour violation (LFV) is one of the most trending topics to probe new physics (NP). The powerful accelerators have enhanced their intensities to observe the LFV decays very precisely. In this situation, the theorists are also interested to study these decays in various NP models and in model independent way to get precise results. Motivated by these results we have studied B decays into K2^star(1430)l1 l2 in non-universal Z^' model. Here, we have structured the two-fold angular distribution of the decays in terms of transversity amplitudes and the transversity amplitudes are formed with NP Wilson coefficients. The variation of the branching ratios and forward backward asymmetries show the sensitivity of NP. The observables calculated in this work are very interesting and might provide a new way towards NP.

   hep-phMod.Phys.Lett.A(2023)·1 citation
6. 06*

   WIMPs, FIMPs, and Inflaton phenomenology via reheating, CMB and $\Delta N_{eff}$

   MD Riajul Haque🇮🇳 · Debaprasad Maity🇮🇳 · Rajesh Mondal🇮🇳

   In this paper, we extensively analyzed the reheating dynamics after inflation and looked into its possible implication on dark matter (DM) and inflaton phenomenology. We studied the reheating through various possible channels of inflaton going into massless scalars (bosonic reheating) and fermions (fermionic reheating) via non-gravitational and gravity-mediated decay processes. We further include the finite temperature effect on the decay process. Along with their precise roles in governing the dynamics, we compared the relative importance of different temperature-corrected decay channels in the gradual process of reheating depending on the reheating equation of state (EoS), which is directly related to inflaton potential. Particularly, the universal gravitational decay of inflaton is observed to play a very crucial role in the reheating process for a large range of inflaton decay parameters. For our study, we consider typical $\alpha$-attractor inflationary models. We further establish the intriguing connection among those different inflaton decay channels and the CMB power spectrum that can have profound implications in building up a unified model of inflation, reheating, and DM. We analyze both fermion and scalar DM with different physical processes being involved, such as gravitational scattering, thermal bath scattering, and direct inflaton decay. Gravitational decay can again be observed to play a crucial role in setting the maximum limit on DM mass that has already been observed earlier in the literature [52]. Depending on the coupling strength, we have analyzed in detail the production of both FIMP and WIMP-like DM during reheating and their detailed phenomenological implications from the perspective of various cosmological and laboratory experiments.

   hep-phastro-ph.COgr-qchep-thJHEP(2023)·72 citations
7. 07*

   Rapidity-only TMD factorization at one loop

   Ian Balitsky🇺🇸

   Typically, a production of a particle with a small transverse momentum in hadron-hadron collisions is described by CSS-based TMD factorization at moderate Bjorken $x_B\sim 1$ and by $k_T$-factorization at small $x_B$. A uniform description valid for all $x_B$ is provided by rapidity-only TMD factorization developed in a series of recent papers at the tree level. In this paper the rapidity-only TMD factorization for particle production by gluon fusion is extended to the one-loop level.

   hep-phJHEP(2023)·14 citations
8. 08*

   Refactorisation in subleading $\bar{B}\to X_s\gamma$

   Tobias Hurth🇩🇪 · Robert Szafron🇺🇸

   We establish refactorisation conditions between the subleading $O_8$-$O_8$ contributions to the inclusive $\bar{B}\to X_s\gamma$ decay suffering from endpoint divergences and prove a factorisation theorem for these contributions to all orders in the strong coupling constant. This allows for higher-order calculations of the resolved contributions and consistent summation of large logarithms, consequently reducing the recently found large-scale dependence in these contributions. We implement the concept of refactorisation in a heavy flavour application of SCET, which includes nonperturbative functions as additional subtlety not present in collider applications.

   hep-phhep-thNPB(2023)·32 citations
9. 09*

   Status of leptoquark models after LHC Run-2 and discovery prospects at future colliders

   Nishita Desai🇮🇳 · Amartya Sengupta🇮🇳

   We study limits from dilepton searches on leptoquark completions to the Standard Model in the parameter space motivated by anomalies in the $b\to s$ sector. After a full Run-2 analysis by LHCb, the disparity in lepton flavour violation has disappeared. However, the mismatch in angular distributions as well as in $B_s\to {\mu }^{+}{\mu }^{-}$ partial width is still unresolved and still implies a possible new physics contribution. We probe three models of leptoquarks -- scalar models $S_3$ and $R_2$ as well as vector leptoquark model $U_1$ using non-resonant dilepton searches to place limit on both the mass and couplings to SM fermions. The exclusions of leptoquarks coupling either non-uniformly to different lepton flavours or uniformly is examined. Interestingly, if leptoquark couplings to electrons and muons are indeed universal, then the $U_1$ model parameter space that corresponds to the anomalous contribution should already accessible with Run-2 data in the non-resonant $e\mu$ channel. In the non-universal case, there is a significant exclusion in couplings, but not enough to reach regions that explain observed anomalies. We, therefore, examine the prospective sensitivity at the HL-LHC as well as of a 3 TeV future muon collider. For the vector leptoquark model, we find that a muon collider can probe all of the relevant parameter space at 95% confidence with just 1 fb${}^{-1}$ data whereas $R_2$ and $S_3$ models can be excluded at 95% with 5 fb${}^{-1}$ and 6.5 fb${}^{-1}$ luminosity respectively.

   hep-ph16 citations
10. 10*

    Superradiant axion clouds around asteroid-mass primordial black holes

    Nuno P. Branco🇵🇹 · Ricardo Z. Ferreira🇪🇸 · João G. Rosa🇵🇹

    We analyze the dynamics and observational signatures of axion clouds formed via the superradiant instability around primordial black holes, focusing on the mass range $10^{14}-10^{18}$ kg where the latter may account for all the dark matter. We take into account the leading effects of axion self-interactions, showing that, even though these limit the number of axions produced within each cloud, a large number of superradiant axions become free of the black hole's gravitational potential and accumulate in the intergalactic medium or even in the host galaxy, depending on their escape velocity. This means that primordial black hole dark matter may lead to a sizeable astrophysical population of non-relativistic axions, with masses ranging from 0.1 eV to 1 MeV, depending on the primordial black hole mass and spin. We then show that if such axions couple to photons their contribution to the galactic and extragalactic background flux, mainly in the X-ray and gamma-ray band of the spectrum, is already beyond current observational limits for a large range of parameters that are, therefore, excluded. We finish by showing the prospects of the Athena X-ray telescope to further probe this co-existence of primordial black holes and axions.

    hep-phastro-ph.COgr-qcJCAP(2023)·39 citations
11. 11*

    Nucleon Energy Correlators for the Color Glass Condensate

    Hao-Yu Liu🇨🇳 · Xiaohui Liu🇨🇳 · Ji-Chen Pan🇨🇳 · Feng Yuan🇺🇸 · Hua Xing Zhu🇨🇳

    We demonstrate the recently proposed nucleon energy-energy correlator (nucleon EEC) $f_{\mathrm{EEC}}(x,\theta )$ can unveil the gluon saturation in the small-$x$ regime in $eA$ collisions. The novelty of this probe is that it is fully inclusive just like the deep-inelastic scattering (DIS), with no requirements of jets or hadrons, but still provides an evident portal to the small-$x$ dynamics through the shape of the $\theta$-distribution. We find that the saturation prediction is significantly different from the expectation of the collinear factorization.

    hep-phhep-exnucl-exnucl-thPRL(2023)·78 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.